The Clinically Isolated Syndrome may represent the initial presentation for multiple sclerosis.

Features of the clinically isolated syndrome:

(1) a monophasic clinical episode

(2) focal or multifocal inflammatory demyelinating event in the CNS, with one or more lesions seen on MRI

(3) may be acute or subacute

(4) duration >= 24 hours

(5) with or without clinical recovery

(6) without fever or infection

(7) no previous diagnosis of multiple sclerosis


Presentations may include:

(1) unilateral or bilateral optic neuritis

(2) focal supratentorial syndrome

(3) focal brainstem syndrome

(4) focal cerebellar syndrome

(5) partial or complete myelopathy

(6) encephalopathy

(7) complete ophthalmoplegia


Most patients with the clinically isolated syndrome progress to multiple sclerosis, in which case the initial presentation is considered the first clinical episode. The progression may be early or very late (up to 20 years) after the first episode.

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